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Production Quality of WW2 Aircraft


dov
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7 hours ago, Blimpyboy said:

Like the lack of ejection seats for some of the aircrew of Victors and Vulcans...!

 

Two good friends in my teenage years were both fatherless as a result of this.  Although both fathers were in Valiants, IIRC...

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I read of a bus garage that was turned over to producing Halifax Cockpits. This was in a book of war memoirs. He said they built 35 before they got it right.

On one of the Avenger production lines the jig had been assembled wrongly, this meant that a particular frame on every Aircraft they built  was misaligned.

 

 

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11 minutes ago, Pete in Lincs said:

I read of a bus garage that was turned over to producing Halifax Cockpits.

 

I wonder if this is a reference to the London Transport Production Board, which did indeed build Mk.II Halifaxes.  This was in their main workshop I believe, but the cockpits are something that could indeed have been built in another site elsewhere.  The British heavies were built to be easily broken down for transport: the fuselage had two transport joints.  The first piece was the nose to the rear of the cockpit, the centre section included the bombbay and the final piece as to the tail gun position.  So each of these could have been built in separate establishments and then assembled in the largest building.

 

It is claimed that they were the least well-built Halifaxes, with the English Electric ones being the best.

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1 minute ago, Graham Boak said:

could indeed have been built in another site elsewhere

I think it was in one of the 'backroom boys' books that I have. I got the impression that it was a rural bus garage/workshop. 

It was probably, as you detail, the nose section. It seemed to me that training was somewhat insufficient.

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I was told by an ex-Lancaster crew-member that the airframes were expected to last for 25 missions. As we all know, some went on to 100+ missions. 

 

Chris.  

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When I was serving my apprenticeship with NZNAC in the sixties our fleet was primarily DC-3 variants for which, even at that time, parts were becoming hard to obtain.

Job lots of spares were purchased, usually from the States, and usually comprising parts manufactured during WW2 or immediately Post war to wartime contracts.

The rejection rate by NAC inspectors was quite high. I specifically recall lots of wing angles - the only bit that holds the wing on - being taken to the dump due to the

counterboring of the bolt holes being too deep. As these parts were available for sale it is reasonable to assume that they had passed inspection at the manufacturer and

would have been used on airframes had hostilities continued.

 

As an aside, I believe the wartime DC-3 did have a bit of a reputation for shedding wings........

Edited by Kiwidave4
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9 hours ago, Jure Miljevic said:

Hello

Bear in mind that in WWII aircraft were not expected to last. I think Mustang had had design limit of 800 hours. I also remember reading in one of the books about SAAF that Liberators in their bomber squadrons had been struck off charge after 500 hours. No doubt, some good machines had been scrapped before their time, but not many lasted that long anyway.

Still, such numbers pale in comparison with late war German production. There is an old anecdote about Bf 109 G fighters Switzerland bought in 1944. Allegedly they complained about a component, which failed after 16 hours. In the laconic answer from the manufacturer it had been explained, that it was designed to fail after eight hours. This is exaggeration, of course, but there is a cold calculation behind such thinking. Why waste man hours and raw material on planes, designed to serve for years, when attrition and obsolescence would eliminate them rather sooner than later. Cheers

Jure

This is quite a true point. I did some fatigue analysis when I was working in structural mechanics at Grumman in the 80s, The resident expert explained that fatigue analysis was a peace-time luxury. Exactly as described above, wartime production doesn't worry about a particularly  long life, certainly not like typical modern lifespans.

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On 6/16/2021 at 1:27 PM, spruecutter96 said:

I remember seeing photos of the rear-gunner's position in a restored Il-2. It was just a thin strip of leather for him to sit on. No lap-belt or any other restraining-devices at all! Let's say that "Health and Safety" was not a major issue for Russian designers at the time. 

 

Chris. 

As was the TAGs cockpit in the Blackburn Skua.  Seat was a webbing or leather strap across the fuselage, harness was a waist belt with an strap down the a shackle on the floor (of course I only found this out after I had glued and filled my latest SH Skua).

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15 hours ago, Jure Miljevic said:

 

Still, such numbers pale in comparison with late war German production...

 

Indeed. Dispersed production, made necessary by Allied bombing, brought its own problems, with badly made components not fitting, equipment being ruined through poor storage conditions, and rushed final assembly. All compounded by a tired, non-expert workforce (including forced labour) being drafted in. 

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17 hours ago, Jure Miljevic said:

Bear in mind that in WWII aircraft were not expected to last. I think Mustang had had design limit of 800 hours. I also remember reading in one of the books about SAAF that Liberators in their bomber squadrons had been struck off charge after 500 hours. No doubt, some good machines had been scrapped before their time, but not many lasted that long anyway.

That's an issue that often comes up in the field of 'warbirds,' the restoration of (chiefly) WW2-era aircraft. The directive was to get as much operational equipment to the front lines 'right now'...not crafting a machine that would be expected to have a decade-long service life. Certain 'expediencies' were perhaps to be expected...though the idea of things like 'missing rivets' is just terrifying.

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I am highly impressed by all the answers all over our planet.

It is far exceeding my knowledge.

If you recall the production faults on Halifax, Sunderland, DC-3 and others.

If I conclude all the messages together, as a sum up, so it is quite sure, that many aircrew losses are caused by faulty production.

 

To take this results to our present:

As I wrote in another threat concerning the loss of the FAA Sea Fury:

Present day airworthy warbirds should / must undergo a redesign and reproduction before restoration (material fatigue & internal corrosion) procedure to make them safe.

One example is the Me 262 from Seattle. In this case the design of the nose wheel was actually wrong.

 

Happy modelling

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1 hour ago, dov said:

Present day airworthy warbirds should / must undergo a redesign and reproduction before restoration (material fatigue & internal corrosion) procedure to make them safe.

 

I think you're wrong on that. 
Even with the relatively high demands the CAA has, an engine mishap does not relate to what you specify here, nor does it take into consideration following proper procedures regardless of type or age. 
We've seen several high-profile cases where your proposed measures wouldn't have helped one bit because the folks running the a/c did not follow their own procedures at all.

It happened with the SA Lightnings, the recent Collings Nine 'o Nine B-17 crash and numerous other mishaps. 

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Low production standards need not read across to aircraft being lost.  Uncomfortable, poorer performing, poor handling, more draughty, shorter repair times, unbalanced trim are all possible effects not leading to dramatic results.  Even in wartime, there was a strong emphasis on superior quality standards being applied in critical areas.  Perhaps one case is the aluminium tank engine heads on the T-34, something beyond Western technology of the time, yet the instrument panels in the Lavochkin fighters (and presumably others) were mounted on largely unprepared wood - less surprising considered the aircraft was largely made out of wood anyway.  Many lesser faults will have been noticed during preparation for or during production flight test trials, or would spotted and replaced/improved in service.

 

I don't know of any significant number of, or reputation for, wing failures on the wartime DC-3.  That many continued in service for many years with operators of doubtful maintenance standards perhaps shows this.  I wonder if this is a case of modern standards simply being higher than older ones, perhaps tolerances being tighter?  There is also a possible matter of life expectancy, with such parts being replaced sooner when built to lower standards.  Or, more cynically, that less care was taken with parts being built for spares than those being built for the assembly line?

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Hello

dnl42, working in capacity as described at Grumman sounds like very desirable job to me. I know this was before your time there, but I always wondered, how much Robert (Bob) Hall influenced design of Grumman aircraft. In his early days Hall designed Granville Gee Bee model Z racer, which was basically the most powerful engine available, pilot's seat and little else.

IanC, I think that under circumstances German aircraft industry did very well indeed. Short of manpower and every raw material imaginable, their industry being bombed day and night, their transport system under ever increasing pressure, and without any source of fuel after February 1945 (loss of coal mines in Śląsk/Slezsko/Schlesien region, which supplied coal to synthetic fuel plants) it is surprising that even in the last year of the war production rates had been increasing until just before the end of the war. What I was talking about is deliberate reduction of quality not to waste resources. Also, think about the low key production of He 219 night fighter against mass produced Ju 88 variants. Admittedly, there were also other factors at work there, but while excellent He 219 stood realistic chance of catching relatively low numbers of Mosquitos, it was average, but still adequate Ju 88, which did most of the fighting against slower, but much more numerous RAF four engined heavy bombers. Cheers

Jure

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The following passage is part of an RAE Technical Note report from September 1943.

 

A comparison of three production Spitfires with Spitfire EN 964 (modified at the Royal Aircraft Establishment} was made recently. These three aircraft were selected as representative of current production at each of the three main Spitfire production firms.  Visual and flight test comparisons of equipment and quality of finish were made. It was pointed out that the aircraft from Westland Aircraft Ltd., (Spitfire EF644) was considerably below the standard of finish of the other aircraft.  It was later discovered that, this aircraft had been selected during a period of change over to different finishing processes. Another aircraft EF731 has therefore been selected from more recent production at Westland Aircraft Ltd., and this note gives visual and flight test comparisons similar to those adopted in Ref. l.

 

Build standard and quality of finish had effects on performance and this report shows that it was taken seriously.

As a modeller the following passages also make me smile.

 

The leading edge 'crack' has been very carefully filled and rubbed down, but slight ridges can be detected along certain sections of the span on the port wing. The leading edge is somewhat flattened where the, curvature should be greatest,

 

The slight depressions formed by the countersunk rivets have been well filled.

 

This aircraft has desert camouflage on the upper surfaces and sky blue undersurfaces. The quality of the paintwork is of an exceptionally high standard for a production Spitfire. The paint has been very carefully applied, The rubbing down has been done thoroughly and there are no roughnesses or ridges, even at the edges of the identification roundels. The smooth finish on EF731 is considered to be up to the standard of EN946,

 

The fitting of the panels on the wing surfaces is very good. All panels lie flush with the wing surfaces and the gaps at the joints are very small,

 

The riveting on the fuselage is fairly good. The inspection doors fit fairly well but the one on the starboard side projects slightly above the fuselage surface. The paintwork is of the same high standard as on the wing surfaces.

 

As we modellers say "There is a prototype for everything".

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4 hours ago, Jure Miljevic said:

 

Also, think about the low key production of He 219 night fighter against mass produced Ju 88 variants. Admittedly, there were also other factors at work there, but while excellent He 219 stood realistic chance of catching relatively low numbers of Mosquitos, it was average, but still adequate Ju 88, which did most of the fighting against slower, but much more numerous RAF four engined heavy bombers.

However, the superior He.219 was also more difficult/expensive/slower to produce, and relied upon the DB603 which was in great demand and short supply.

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4 hours ago, Jure Miljevic said:

 

IanC, I think that under circumstances German aircraft industry did very well indeed. Short of manpower and every raw material imaginable, their industry being bombed day and night, their transport system under ever increasing pressure, and without any source of fuel after February 1945 (loss of coal mines in Śląsk/Slezsko/Schlesien region, which supplied coal to synthetic fuel plants) it is surprising that even in the last year of the war production rates had been increasing until just before the end of the war. What I was talking about is deliberate reduction of quality not to waste resources. 

 

Absolutely. The fighter programme was a success compared to what had gone before, despite the bombing. But ultimately to little avail, of course, because of the catastrophic decline in pilot numbers and quality, and the deteriorating fuel situation. 

 

 

 

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On 6/19/2021 at 4:45 PM, spruecutter96 said:

Didn't one of the very early prototypes of the Heinkel He-126 "Peoples' Fighter" have the leading-edge of its wing fall off, when it was being demonstrated to a number of Luftwaffe generals? IIRC, the pilot didn't survive the incident. This is perhaps not too surprising considering that it went from concept to flight in just a few months.

 

Chris.  

Typo: He.162.  This incident was very puzzling, but it wasn't a matter of low production - or even prototype - workmanship.  Those given the job of determining the cause of the crash were unable to explain the dynamics of the aircraft behaviour using the aerodynamic and structural knowledge of the time, other than that the wing failure was a result rather than a cause.  (I believe that there was a similar crash during post-war flights at RAE Farnborough, but don't quote me on that without checking!)  It took some years work postwar by a German aerodynamicist (W.G. Pinker?  name from memory and therefore doubtful) at RAE Farnborough to come up with a mathematical explanation of something called inertia coupling: this may have been hastened (I don't know) by US studies into the failure of an early F-100 from what turned out to have the same explanation (as appropriate to type).  However it has ever since been taken into account in the design of modern aircraft.  I strongly suspect that this was also the cause of the unsatisfactory behaviour of WW2 aircraft with heavy weapons mounted outboard and under the wing.

 

Without getting too technical, which I am not qualified to do anyway, the basic cause was having a large mass situated some way away from the normal pitch/roll/yaw axes of the aircraft. i.e. the engine mounted above the fuselage.  Think of it as a pair of dumbbells that you are trying to whirl around, but holding them at an angle.  The force generated by this asymmetry takes over from the normal aerodynamic forces resulting in violent unexpected movement in all axes and structural failure of the aircraft.  Or your wrist, perhaps.  My apologies for the inadequate nature of this explanation.

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IIUC, the dominant examples of poor production directly causing aircraft loss were in Germany. In A Higher Call,  F. Stigler explicitly cites special considerations for Me-262 engine operations to mitigate poor construction, due in part to sabotage by slave labor. I'm certain there were examples US and British losses due to poor materials or construction, but those are most likely the extreme examples always found in large numbers.

 

As cited above, design and production requirements are much more stringent today, the operational envelopes are far more extreme; 1940 design and analysis methods as well as manufacturing processes pale in comparison. I spent many weeks with another engineer analyzing an F-14 bulkhead while at Grumman, including the construction of a detailed 3-D finite element model--somewhat advanced for the time--and the application of correspondingly complex loads. To be sure, our work only generated data that enabled senior structural analysts to develop the final analysis package. The F-14 wing box was a marvel of electron-beam welded titanium. Additive manufacturing--3-D printed metal parts--are increasingly used in aerospace. Computer-optimized designs can have strength and weight characteristics exceeding what the most capable design engineer would be able to create.

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This is little off topic, but also not a million miles away from it.....

 

I remember reading an interview an anonymous ex-Soviet nuclear submarine crew-man, many years ago. He said that, at the start of a mission, the entire crew were given badges designed to turn black when they were subjected to high levels of radiation. After 4 or 5 days of wearing the badges, they would all turn black. When this crew-member told the boat's doctor about it, the medic gave him a brand-new badge to wear and instructed him not to worry about it. Apparently, the cancer rates of his crew-mates in the following years were extremely high. 

 

I'm guessing that the radiation-shielding on the early Russian atomic boats could have been more effective than it was.

 

Chris.    

 

PS: I have also read that Russian Tupolev Tu-95 bomber crews have a very high probability of going deaf, due to the presence of four enormous engines fitted with contra-rotating airscrews less than 100 feet away from their ears. The sound of the Russian "Bear" can apparently even be heard by intercepting NATO pilots, if they fly close enough to the massive intruder. You have to bear in mind that the NATO pilots are flying very noisy jets themselves and are wearing helmets designed to keep extraneous noise out. 

 

 

Edited by spruecutter96
Amending some information.
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Hallo

 

All your inputs sound very interesting. For me, I learn with all your answers.

Today I want to give you some input in production. Myself I also worked for some years in the production line. Different subject, different time, but the pattern is the same.

Just in time for the automotive industry in 1990 for two years.

In each production you must achieve at the end of a shift a certain amount of products which meet the quality standards.

To achieve this goal is the purpose. The money at the end of a summery of shifts you earn is one part.

On the other end, you have to consider a production chain.

If one factory does not meet the quantity assigned to, all the other factories will get in trouble and will also not reach the assigned quantity.

As a human in the production line in any factory, you are confronted with faulty items.

In each shift. You can claim for this faulty items, you get replacement for this items or not.

If not, you will not be able to produce the assigned quantity of products at the end of your shift.

 

Who takes the responsibility and corrects the quantity?

Pressure from the top of any production company is sure!

Much pressure. Even today under ISO 9000 standards.

At the time of war, the word of sabotage was very close.

To avoid it, many workers in each factory became inventive to handle faulty items. To bypass every record!

Without letting anybody else know. This is the real human and psychological factor in any production process.

If you ever had to work on an assembly line, you will understand my words.

If not, so consider it at today if a company looses each day many 1000 of Euro or Dollar.

Who takes the responsibility? The share holder will beat you!

At times of war you had in Germany the Gestapo, and in Russia some other people.

In allied lands someone else.

 

Happy modelling

 

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Can't remember the exact source for this, must be one of my Yefim Gordon books.  It's a (famous) story by Yakovlev, brought before Stalin in late 1942.  On Stalin's desk are pieces of Yak fighters, whose leading edges have shed the glued-on cloth that apparently covered the wood.  Stalin informs Yakovlev that 'only our country's mist bitter enemies could have brought about this situation'.  Yakovlev heeds the message and the pragmatic, if paranoid, dictator allows him to 'fix' the production line issues (which are related to lack of supplies of needed chemicals, and the obvious need to get fighters finished and to the front line.  Gordon's books also detail the troubled situation with Lavochkin's LaGG-3s, which are never able to produce their design  performance due to poor quality.  This is reported in some detail by investigations, but in the end it seems to come down to the skills and experience of the workers.

 

And this is the key: in 1941-42, virtually every aeroplane production line worker in the world was pretty new at their job. Most planes were coming out of very new factories, with enormous pressure to hit production targets.  Clearly, there were so many very different sets of conditions applying, across the world. 

 

Another favourite book of mine, The Relentless Offensive, details Arthur Harris's constant efforts to get Halifaxes improved and bombers generally fitted with effective defensive weapons.  In a memorable letter and in light of the Yakovlev story above, he urged Churchill to consider the persistent refusal/inability of Handley Page to improve the quality of Halifaxes, noting that Stalin would have those responsible for such sabotage shot.

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I don't know if this is true, but I read some time ago that Stalin was very keen on the idea of a "flying submarine". He asked his scientists if a vehicle could be made that could travel through the air and underwater. The legend continues that his experts had to VERY diplomatically inform him that such a machine could not be invented. I bet they were sweating profusely when they delivered that news to their leader.   

Chris. 

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